Modding-wise, it pretty much allows a complete overhaul of the game universe. You can make your own tech trees, resources, components, government types, create your own galaxy map including special locations, write your own storyline including creating triggered events similar to what we have in the official storylines. -Erik Rutins (Matrix Games’ Director of Product Development)

And as for new game content:

It will also include a new official storyline, covering the first war between the Freedom Alliance and the Shaktur Axis, in which, among other things, you’ll have access to the tech required to build your own planet destroyers and research and deploy the Xaraktor virus.